An effective and fast soccer ball detection and tracking method

A ball detection and tracking approach in real soccer game is proposed in this paper. In view of difficulties of direct detection, an indirect strategy based on non-ball elimination is applied. We distinguish the ball with a coarse-to-fine process. Game field is firstly extracted and the posterior operations are restricted within it. Then, at the coarse step, some distinct non-ball regions are removed via evaluation of color and shape. And at the fine step, the remained regions are further examined and the optimal one is determined as ball. Afterwards. CONDENSATION algorithm is utilized to track ball. Region optimization is appended to adapt to the ball's size and color/texture changes in response to movement along sequential frames through maximizing the normalization sum of intensity gradient around its perimeter. Moreover, a confidence measure representing the ball region's reliability is presented to guide possible re-detection for continuous tracking. Experiments have demonstrated the method is valid and fast in real soccer sequences.